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2c020ed8 CM |
1 | /* |
2 | * Based on arch/arm/kernel/signal.c | |
3 | * | |
4 | * Copyright (C) 1995-2009 Russell King | |
5 | * Copyright (C) 2012 ARM Ltd. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
18 | */ | |
19 | ||
20 | #include <linux/errno.h> | |
21 | #include <linux/signal.h> | |
22 | #include <linux/personality.h> | |
23 | #include <linux/freezer.h> | |
24 | #include <linux/uaccess.h> | |
25 | #include <linux/tracehook.h> | |
26 | #include <linux/ratelimit.h> | |
27 | ||
28 | #include <asm/compat.h> | |
29 | #include <asm/debug-monitors.h> | |
30 | #include <asm/elf.h> | |
31 | #include <asm/cacheflush.h> | |
32 | #include <asm/ucontext.h> | |
33 | #include <asm/unistd.h> | |
34 | #include <asm/fpsimd.h> | |
35 | #include <asm/signal32.h> | |
36 | #include <asm/vdso.h> | |
37 | ||
38 | /* | |
39 | * Do a signal return; undo the signal stack. These are aligned to 128-bit. | |
40 | */ | |
41 | struct rt_sigframe { | |
42 | struct siginfo info; | |
43 | struct ucontext uc; | |
304ef4e8 WD |
44 | u64 fp; |
45 | u64 lr; | |
2c020ed8 CM |
46 | }; |
47 | ||
48 | static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) | |
49 | { | |
50 | struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state; | |
51 | int err; | |
52 | ||
53 | /* dump the hardware registers to the fpsimd_state structure */ | |
54 | fpsimd_save_state(fpsimd); | |
55 | ||
56 | /* copy the FP and status/control registers */ | |
57 | err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); | |
58 | __put_user_error(fpsimd->fpsr, &ctx->fpsr, err); | |
59 | __put_user_error(fpsimd->fpcr, &ctx->fpcr, err); | |
60 | ||
61 | /* copy the magic/size information */ | |
62 | __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err); | |
63 | __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err); | |
64 | ||
65 | return err ? -EFAULT : 0; | |
66 | } | |
67 | ||
68 | static int restore_fpsimd_context(struct fpsimd_context __user *ctx) | |
69 | { | |
70 | struct fpsimd_state fpsimd; | |
71 | __u32 magic, size; | |
72 | int err = 0; | |
73 | ||
74 | /* check the magic/size information */ | |
75 | __get_user_error(magic, &ctx->head.magic, err); | |
76 | __get_user_error(size, &ctx->head.size, err); | |
77 | if (err) | |
78 | return -EFAULT; | |
79 | if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context)) | |
80 | return -EINVAL; | |
81 | ||
82 | /* copy the FP and status/control registers */ | |
83 | err = __copy_from_user(fpsimd.vregs, ctx->vregs, | |
84 | sizeof(fpsimd.vregs)); | |
85 | __get_user_error(fpsimd.fpsr, &ctx->fpsr, err); | |
86 | __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); | |
87 | ||
88 | /* load the hardware registers from the fpsimd_state structure */ | |
89 | if (!err) { | |
90 | preempt_disable(); | |
91 | fpsimd_load_state(&fpsimd); | |
92 | preempt_enable(); | |
93 | } | |
94 | ||
95 | return err ? -EFAULT : 0; | |
96 | } | |
97 | ||
98 | static int restore_sigframe(struct pt_regs *regs, | |
99 | struct rt_sigframe __user *sf) | |
100 | { | |
101 | sigset_t set; | |
102 | int i, err; | |
103 | struct aux_context __user *aux = | |
104 | (struct aux_context __user *)sf->uc.uc_mcontext.__reserved; | |
105 | ||
106 | err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); | |
107 | if (err == 0) | |
108 | set_current_blocked(&set); | |
109 | ||
110 | for (i = 0; i < 31; i++) | |
111 | __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], | |
112 | err); | |
113 | __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); | |
114 | __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); | |
115 | __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); | |
116 | ||
117 | /* | |
118 | * Avoid sys_rt_sigreturn() restarting. | |
119 | */ | |
120 | regs->syscallno = ~0UL; | |
121 | ||
122 | err |= !valid_user_regs(®s->user_regs); | |
123 | ||
124 | if (err == 0) | |
125 | err |= restore_fpsimd_context(&aux->fpsimd); | |
126 | ||
127 | return err; | |
128 | } | |
129 | ||
130 | asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) | |
131 | { | |
132 | struct rt_sigframe __user *frame; | |
133 | ||
134 | /* Always make any pending restarted system calls return -EINTR */ | |
135 | current_thread_info()->restart_block.fn = do_no_restart_syscall; | |
136 | ||
137 | /* | |
138 | * Since we stacked the signal on a 128-bit boundary, then 'sp' should | |
139 | * be word aligned here. | |
140 | */ | |
141 | if (regs->sp & 15) | |
142 | goto badframe; | |
143 | ||
144 | frame = (struct rt_sigframe __user *)regs->sp; | |
145 | ||
146 | if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) | |
147 | goto badframe; | |
148 | ||
149 | if (restore_sigframe(regs, frame)) | |
150 | goto badframe; | |
151 | ||
207bdae4 | 152 | if (restore_altstack(&frame->uc.uc_stack)) |
2c020ed8 CM |
153 | goto badframe; |
154 | ||
155 | return regs->regs[0]; | |
156 | ||
157 | badframe: | |
158 | if (show_unhandled_signals) | |
159 | pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n", | |
160 | current->comm, task_pid_nr(current), __func__, | |
161 | regs->pc, regs->sp); | |
162 | force_sig(SIGSEGV, current); | |
163 | return 0; | |
164 | } | |
165 | ||
2c020ed8 CM |
166 | static int setup_sigframe(struct rt_sigframe __user *sf, |
167 | struct pt_regs *regs, sigset_t *set) | |
168 | { | |
169 | int i, err = 0; | |
170 | struct aux_context __user *aux = | |
171 | (struct aux_context __user *)sf->uc.uc_mcontext.__reserved; | |
172 | ||
304ef4e8 WD |
173 | /* set up the stack frame for unwinding */ |
174 | __put_user_error(regs->regs[29], &sf->fp, err); | |
175 | __put_user_error(regs->regs[30], &sf->lr, err); | |
176 | ||
2c020ed8 CM |
177 | for (i = 0; i < 31; i++) |
178 | __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], | |
179 | err); | |
180 | __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); | |
181 | __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); | |
182 | __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); | |
183 | ||
184 | __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); | |
185 | ||
186 | err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); | |
187 | ||
188 | if (err == 0) | |
189 | err |= preserve_fpsimd_context(&aux->fpsimd); | |
190 | ||
191 | /* set the "end" magic */ | |
192 | __put_user_error(0, &aux->end.magic, err); | |
193 | __put_user_error(0, &aux->end.size, err); | |
194 | ||
195 | return err; | |
196 | } | |
197 | ||
b64e1c61 WD |
198 | static struct rt_sigframe __user *get_sigframe(struct k_sigaction *ka, |
199 | struct pt_regs *regs) | |
2c020ed8 CM |
200 | { |
201 | unsigned long sp, sp_top; | |
b64e1c61 | 202 | struct rt_sigframe __user *frame; |
2c020ed8 CM |
203 | |
204 | sp = sp_top = regs->sp; | |
205 | ||
206 | /* | |
207 | * This is the X/Open sanctioned signal stack switching. | |
208 | */ | |
209 | if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) | |
210 | sp = sp_top = current->sas_ss_sp + current->sas_ss_size; | |
211 | ||
b64e1c61 WD |
212 | sp = (sp - sizeof(struct rt_sigframe)) & ~15; |
213 | frame = (struct rt_sigframe __user *)sp; | |
2c020ed8 CM |
214 | |
215 | /* | |
216 | * Check that we can actually write to the signal frame. | |
217 | */ | |
218 | if (!access_ok(VERIFY_WRITE, frame, sp_top - sp)) | |
219 | frame = NULL; | |
220 | ||
221 | return frame; | |
222 | } | |
223 | ||
304ef4e8 WD |
224 | static void setup_return(struct pt_regs *regs, struct k_sigaction *ka, |
225 | void __user *frame, int usig) | |
2c020ed8 | 226 | { |
2c020ed8 | 227 | __sigrestore_t sigtramp; |
2c020ed8 CM |
228 | |
229 | regs->regs[0] = usig; | |
2c020ed8 | 230 | regs->sp = (unsigned long)frame; |
304ef4e8 | 231 | regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp); |
2c020ed8 CM |
232 | regs->pc = (unsigned long)ka->sa.sa_handler; |
233 | ||
234 | if (ka->sa.sa_flags & SA_RESTORER) | |
235 | sigtramp = ka->sa.sa_restorer; | |
236 | else | |
237 | sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp); | |
238 | ||
239 | regs->regs[30] = (unsigned long)sigtramp; | |
2c020ed8 CM |
240 | } |
241 | ||
242 | static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, | |
243 | sigset_t *set, struct pt_regs *regs) | |
244 | { | |
245 | struct rt_sigframe __user *frame; | |
2c020ed8 CM |
246 | int err = 0; |
247 | ||
b64e1c61 | 248 | frame = get_sigframe(ka, regs); |
2c020ed8 CM |
249 | if (!frame) |
250 | return 1; | |
251 | ||
252 | __put_user_error(0, &frame->uc.uc_flags, err); | |
253 | __put_user_error(NULL, &frame->uc.uc_link, err); | |
254 | ||
207bdae4 | 255 | err |= __save_altstack(&frame->uc.uc_stack, regs->sp); |
2c020ed8 | 256 | err |= setup_sigframe(frame, regs, set); |
304ef4e8 WD |
257 | if (err == 0) { |
258 | setup_return(regs, ka, frame, usig); | |
259 | if (ka->sa.sa_flags & SA_SIGINFO) { | |
260 | err |= copy_siginfo_to_user(&frame->info, info); | |
261 | regs->regs[1] = (unsigned long)&frame->info; | |
262 | regs->regs[2] = (unsigned long)&frame->uc; | |
263 | } | |
2c020ed8 CM |
264 | } |
265 | ||
266 | return err; | |
267 | } | |
268 | ||
269 | static void setup_restart_syscall(struct pt_regs *regs) | |
270 | { | |
271 | if (is_compat_task()) | |
272 | compat_setup_restart_syscall(regs); | |
273 | else | |
274 | regs->regs[8] = __NR_restart_syscall; | |
275 | } | |
276 | ||
277 | /* | |
278 | * OK, we're invoking a handler | |
279 | */ | |
280 | static void handle_signal(unsigned long sig, struct k_sigaction *ka, | |
281 | siginfo_t *info, struct pt_regs *regs) | |
282 | { | |
283 | struct thread_info *thread = current_thread_info(); | |
284 | struct task_struct *tsk = current; | |
285 | sigset_t *oldset = sigmask_to_save(); | |
286 | int usig = sig; | |
287 | int ret; | |
288 | ||
289 | /* | |
290 | * translate the signal | |
291 | */ | |
292 | if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) | |
293 | usig = thread->exec_domain->signal_invmap[usig]; | |
294 | ||
295 | /* | |
296 | * Set up the stack frame | |
297 | */ | |
298 | if (is_compat_task()) { | |
299 | if (ka->sa.sa_flags & SA_SIGINFO) | |
300 | ret = compat_setup_rt_frame(usig, ka, info, oldset, | |
301 | regs); | |
302 | else | |
303 | ret = compat_setup_frame(usig, ka, oldset, regs); | |
304 | } else { | |
305 | ret = setup_rt_frame(usig, ka, info, oldset, regs); | |
306 | } | |
307 | ||
308 | /* | |
309 | * Check that the resulting registers are actually sane. | |
310 | */ | |
311 | ret |= !valid_user_regs(®s->user_regs); | |
312 | ||
313 | if (ret != 0) { | |
314 | force_sigsegv(sig, tsk); | |
315 | return; | |
316 | } | |
317 | ||
318 | /* | |
319 | * Fast forward the stepping logic so we step into the signal | |
320 | * handler. | |
321 | */ | |
322 | user_fastforward_single_step(tsk); | |
323 | ||
324 | signal_delivered(sig, info, ka, regs, 0); | |
325 | } | |
326 | ||
327 | /* | |
328 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
329 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
330 | * mistake. | |
331 | * | |
332 | * Note that we go through the signals twice: once to check the signals that | |
333 | * the kernel can handle, and then we build all the user-level signal handling | |
334 | * stack-frames in one go after that. | |
335 | */ | |
336 | static void do_signal(struct pt_regs *regs) | |
337 | { | |
338 | unsigned long continue_addr = 0, restart_addr = 0; | |
339 | struct k_sigaction ka; | |
340 | siginfo_t info; | |
341 | int signr, retval = 0; | |
342 | int syscall = (int)regs->syscallno; | |
343 | ||
344 | /* | |
345 | * If we were from a system call, check for system call restarting... | |
346 | */ | |
347 | if (syscall >= 0) { | |
348 | continue_addr = regs->pc; | |
349 | restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4); | |
350 | retval = regs->regs[0]; | |
351 | ||
352 | /* | |
353 | * Avoid additional syscall restarting via ret_to_user. | |
354 | */ | |
355 | regs->syscallno = ~0UL; | |
356 | ||
357 | /* | |
358 | * Prepare for system call restart. We do this here so that a | |
359 | * debugger will see the already changed PC. | |
360 | */ | |
361 | switch (retval) { | |
362 | case -ERESTARTNOHAND: | |
363 | case -ERESTARTSYS: | |
364 | case -ERESTARTNOINTR: | |
365 | case -ERESTART_RESTARTBLOCK: | |
366 | regs->regs[0] = regs->orig_x0; | |
367 | regs->pc = restart_addr; | |
368 | break; | |
369 | } | |
370 | } | |
371 | ||
372 | /* | |
373 | * Get the signal to deliver. When running under ptrace, at this point | |
374 | * the debugger may change all of our registers. | |
375 | */ | |
376 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); | |
377 | if (signr > 0) { | |
378 | /* | |
379 | * Depending on the signal settings, we may need to revert the | |
380 | * decision to restart the system call, but skip this if a | |
381 | * debugger has chosen to restart at a different PC. | |
382 | */ | |
383 | if (regs->pc == restart_addr && | |
384 | (retval == -ERESTARTNOHAND || | |
385 | retval == -ERESTART_RESTARTBLOCK || | |
386 | (retval == -ERESTARTSYS && | |
387 | !(ka.sa.sa_flags & SA_RESTART)))) { | |
388 | regs->regs[0] = -EINTR; | |
389 | regs->pc = continue_addr; | |
390 | } | |
391 | ||
392 | handle_signal(signr, &ka, &info, regs); | |
393 | return; | |
394 | } | |
395 | ||
396 | /* | |
397 | * Handle restarting a different system call. As above, if a debugger | |
398 | * has chosen to restart at a different PC, ignore the restart. | |
399 | */ | |
400 | if (syscall >= 0 && regs->pc == restart_addr) { | |
401 | if (retval == -ERESTART_RESTARTBLOCK) | |
402 | setup_restart_syscall(regs); | |
403 | user_rewind_single_step(current); | |
404 | } | |
405 | ||
406 | restore_saved_sigmask(); | |
407 | } | |
408 | ||
409 | asmlinkage void do_notify_resume(struct pt_regs *regs, | |
410 | unsigned int thread_flags) | |
411 | { | |
412 | if (thread_flags & _TIF_SIGPENDING) | |
413 | do_signal(regs); | |
414 | ||
415 | if (thread_flags & _TIF_NOTIFY_RESUME) { | |
416 | clear_thread_flag(TIF_NOTIFY_RESUME); | |
417 | tracehook_notify_resume(regs); | |
418 | } | |
419 | } |